Amazon has the 4-Pack of Purex Crystals In-Wash Fragrance & Scent Booster (21oz each, Fresh Vibes) for $15.88 - 5% off with Subscribe & Save (can cancel anytime) - $4.32 off coupon (check “Save an extra” box, eligible on first S&S order for this product) = $10.77 with free shipping on $25+ or with Prime.